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Novotny, V.

Publications and source records attributed to Novotny, V..

5 recordsLinked to original sources
bioRxiv2026

Spatial turnover amplifies with trophic level in hyperdiverse food webs

One of the most intuitive ideas in ecology is that diversity at lower trophic levels in food webs provides niches to support diversity at higher trophic levels. This accumulation of diversity can be limited by survival of species in the landscape, but revealing these limits has been challenging. We analyze spatial turnover in a hyperdiverse parasitoid-caterpillar-plant food web across 75,000 km2 of continuous lowland rainforest in Papua New Guinea. Species turnover across sites is higher in parasitoids than in their caterpillar hosts. Furthermore, turnover of interactions is also higher in parasitoid-caterpillar than caterpillar-plant networks. Spatial turnover thus amplifies upwards across trophic levels, forcing parasitoids to live closer to spatial persistence limits. Consequently, progressing rainforest fragmentation can especially endanger parasitoids.

ecology↗
bioRxiv2022

Reorganization of bird communities along a rainforest elevation gradient during a strong El Nino event in Papua New Guinea

The El Nino 2015 event, most extreme since 1997, led to severe droughts in tropical wet Papua New Guinea (PNG), reducing May to October dry season rainfall by - 75% in the lowlands and 25% in the highlands. Such droughts are likely to have significant effects on terrestrial ecosystems, but they have been poorly explored in Papua New Guinea. Here we report changes in bird community composition prior, during and after 2015 El Nino event along the elevational gradient ranging from 200 m to 2,700 m a.s.l. at the Mt. Wilhelm rainforest in PNG. The abundance of birds in lowlands dropped by 60% but increased by 40% at elevations above 1700m during El Nino year. In the following year, the individual bird species reached mean population sizes similar to pre-El Nino years but did not fully recover. Species richness roughly followed the pattern of observed abundance and quickly and fully re-established after the event to the pre-El Nino values. Thus, at least some terrestrial birds seem to react quickly to the extreme droughts in lowlands and shifted to less affected mountain habitats. We recorded upper elevational range limits to shifts by more than 500m asl in 22 bird species (out of 237 recorded in total) during El Nino year, in contrast to their typical ranges. Our study suggests that a strong El Nino event can have strong but reversible effects on bird communities as long as they have an opportunity to move to more favourable sites through undisturbed habitats.

ecology↗
bioRxiv2022

Species richness and community structure of bats along a forest elevational transect in Papua New Guinea

Over the past decades, elevational gradients have become a powerful tool with which to understand the underlying cause(s) of biodiversity. The Mt. Wilhelm elevational transect is one such example, having been used to study the birds, insects, and plants of Papua New Guinea (PNG). However, a survey of mammals from this forest elevational transect was lacking. We thus aimed to investigate patterns in the community structure and species richness of bats (Chiroptera) along the transect, link the species to available regional data, and explain the observed patterns by including environmental characteristics. Bat communities were surveyed between 200 m and a timberline at 3,700 m a.s.l. at eight study sites separated by 500 m in elevation. We conducted mist-netting and acoustic surveys to detect and identify species at each site. Regional data were compiled to compare local with regional diversity. Finally, biotic (i.e., food availability, habitat features) and abiotic (i.e., mean daily temperature, available land area) factors were included in our analyses to disentangle the ecological drivers underlying bat diversity. Results revealed that species richness decreases with ascending elevation and was best explained by a corresponding decrease in both area and temperature. We also observed community turnover along the transect at local and regional scales, along with the increase of species elevational ranges. Consequently, despite that the study was restricted to one mountain in PNG, it demonstrates how basic inventory surveys can be used to address ecological questions in other similar and undisturbed tropical mountains.

ecology↗
bioRxiv2021

The world's hotspot of linguistic and biocultural diversity under threat

Papua New Guinea is home to >10% of the worlds languages and rich and varied biocultural knowledge, but the future of this diversity remains unclear. We measured language skills of 6,190 students speaking 392 languages (5.5% of the global total) and modelled their future trends, using individual-level variables characterizing family language use, socio-economic conditions, students skills, and language traits. This approach showed that only 58% of the students, compared to 91% of their parents, were fluent in indigenous languages, while the trends in key drivers of language skills (language use at home, proportion of mixed-language families, urbanization, students traditional skills) predicted accelerating decline of fluency, to an estimated 26% in the next generation of students. Ethnobiological knowledge declined in close parallel with language skills. Varied medicinal plant uses known to the students speaking indigenous languages are replaced by a few, mostly non-native species for the students speaking English or Tok Pisin, the national lingua franca. Most (88%) students want to teach indigenous language to their children. While crucial for keeping languages alive, this intention faces powerful external pressures as key factors (education, cash economy, road networks, urbanization) associated with language attrition are valued in contemporary society. Significance StatementAround the world, more than 7,000 languages are spoken, most of them by small populations of speakers in the tropics. Globalization puts small languages at a disadvantage, but our understanding of the drivers and rate of language loss remains incomplete. When we tested key factors causing language attrition among Papua New Guinean students speaking 392 different indigenous languages, we found an unexpectedly rapid decline in their language skills compared to their parents and predicted further acceleration of language loss in the next generation. Language attrition was accompanied by decline in the traditional knowledge of nature among the students, pointing to an uncertain future for languages and biocultural knowledge in the most linguistically diverse place on Earth.

ecology↗